The present invention relates to lens grinding apparatus.
The present invention relates particularly to apparatus suitable for grinding aspheric lenses.
In conventional grinding apparatus of the above type the lens which is to be ground is carried by a rotary shaft while the surface which is to be ground is engaged by a grinding wheel. The rotary shaft which carries the lens which is to be ground is supported by an oscillating structure which oscillates about an oscillating axis and which carries a template which determines the curvature of the lens surface which is ground.
The axis of the shaft which carries the lens which is to be ground and the oscillating axis about which this shaft is oscillated together with the template are perpendicular to each other. In order to achieve a high accuracy in the grinding of a lens it is essential that the mutually perpendicular shaft axis and oscillating axis intersect each other.
In conventional structures of the above type the adjustments required for assuring intersection between these axes are carried out by relatively complex structures which are inconvenient to operate. Thus with conventional devices of this type the axis adjustment is carried out by using adjusting jigs and the like. These conventional structures are difficult to operate in such a way as to bring about the required adjustment with a high degree of accuracy. Quite often the mutually perpendicular axes of the shaft which carries the lens and the template which is oscillated together with this shaft, while initially intersecting each other, become displaced one with respect to the other, for example due to vibrations of the grinding apparatus, and it is extremely difficult with conventional apparatus to correct the position of these axes with respect to each other so that they intersect each other. Thus, when during operation of such a grinding apparatus the shaft axis and oscillating axis no longer intersect each other, it has proved to be practically impossible to achieve a rapid and accurate readjustment so as to bring the axis of the shaft and the oscillating axis again to a position where they intersect each other.